Current multiboot header has number of problems:
- Bitfields. They place a limit on 16 mandatory and 16 optional
features. This forces us to carefully consider every flag and sometimes
squash marginally related requirements together.
- Whether flag is ignorable or not is a part of specification and can't
be decided by target image. Something that is fatal for one image may be
a workable condition for another one. E.g. if header request that
modules are page-aligned it may be able to handle non-aligned modules
but be much slower for them.
- It doesn't specify architecture.
- Header addresses are fixed so if you want to specify a field at offset
128 but none of fields at lower offset you still have to reserve 132 bytes.
Possible solution is to use tags. Ammendment proposal attached

-- 
Regards
Vladimir 'φ-coder/phcoder' Serbinenko